Saving mouse click coordinates on image in GUI

Hello,

How do I record up to 5 mouse click coordinates ([x,y] relative to the image with (0,0) being in the upper left) on an 512 by 512 image (axes1 of my GUI)? I would like the mouse click locations to be saved in a table, so I can use the values for subsequent calculations.

I found the following script online for saving coordinates, but am not sure how it works and where to put this within the GUI script.

function ImageClickCallback (objectHandle , eventData )
   axesHandle  = get(objectHandle,'Parent');
   coordinates = get(handles.axes1,'CurrentPoint'); 
   coordinates = coordinates(1,1:2);
   %// then here you can use coordinates as you want ...

For the data-capturing table, I suppose I should be doing the following, but I am not sure which callback section to place it under (do I have to manually create a "mouseclick" callback?):

tableData = {x1,y1,z1;x2,y2,z2;x3,y3,z3;x4,y4,z4;x5,y5,z5};
set(handles.CoordinateTable,'Data',tableData)

The Z values refer to the slice number (obtainable from the slider location) since I am showing a stack of images. I believe that after updating the handles, I should be able to perform my calculations from there.

Apologies for the novice question, as I am quite new to MATLAB. Thank you so much!

Answer 1

[Walter Roberson]

You have done well to find that information already. The additional information you need is

http://matlab.wikia.com/wiki/FAQ#How_can_I_share_data_between_callback_functions_in_my_GUI.3F

to allow you to store the various coordinates.

The ImageClickCallback is something that you would configure as a ButtonDownFcn callback on the image.

You could also consider using ginput(5) to get up to 5 coordinates. The biggest difference between that and using a ButtonDownFcn as a callback is that ginput() is an active command that has to be issued by a running function which would wait for the coordinates and then proceed, whereas callback functions are passive, with no function running until the user triggers the action.

[Brian]

I decided to follow the ginput(n) method because it gives a crosshair as well. However, I am unable to get this to work. The crosshair doesn't show on my GUI and it appears no coordinates are saved either. What am I not doing correctly?

% --- Executes on mouse press over axes background.
function axes1_ButtonDownFcn(hObject, eventdata, handles)
% hObject    handle to axes1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
SliderLocation = round(get(handles.slider1,'Value'));
[xlist ylist]=ginput(5);
tableData = {xlist(1),ylist(1),SliderLocation};
set(handles.CoordinateTable,'Data',tableData)

% Update handles structure
guidata(hObject, handles)

The code is just using the first set of coordinates as example. Thank you so much!